Mycotoxins are the toxic metabolites resulting from fungal infestation and growth on cereal grains and can result during growth, harvest, transportation or storage of the grains. While mycotoxins have been a problem for centuries, it was not until 1960 that significant research efforts in the role of mycotoxins in animal production occured. The incident which spurred this interest was the realization of the causal nature of aflatoxins in a disease called Turkey X disease in turkey poults in Great Britain.
Mycotoxin contamination of cereal grains is a relatively common problem. The exact type and extent of the problem is a function of mold types, growing conditions during the crop season and storage practices. Aflatoxins are a mycotoxin of particular concern since aflatoxin B.sub.1 is one of the most potent known hepatocarcinogens. Aflatoxin ingestion is invariably accompanied by a reduction in feed intake and, consequently, a reduction in growth rate of pigs and other animals.
There has been much recent interest in the use of products which are already approved as anticaking agents or pelleting aids in feed manufacturing as ameliorators of the adverse effects of aflatoxin ingestion in swine. A hydrated attapulgite clay (sodium calcium aluminosilicate), selenium, and folic acid (a B-vitamin) presently are used as feed supplements for ameliorating the effects of aflatoxin-contaminated feeds on animals, such as pigs. An attapulgite clay present on the market for this purpose is NOVASIL marketed by Engelhard Corporation, Cleveland, Ohio.
While the acute symptoms of mycotoxins, e.g. aflatoxicosis, in swine are relatively easy to identify and the economic losses evident, the chronic symptoms of slightly diminished performance and immunosuppressive effects probably constitute a much greater economic loss in pork production than for other animals, e.g. beef. Traditional methods of dealing with grains known to be contaminated with mycotoxins are: blending with `clean` grain to reduce the contamination level; screening or other means of physical separation to remove highly contaminated fines; and ammoniation or heating to detoxify the grain. Of more recent interest in the U.S. is the use of products which are already approved as anticaking agents or pelleting aids to reduce the adverse effects of aflatoxin ingestion.
As stated in Kirk-Othmer, Encyclopedia of Chemical Technology, Vol.5, 1964, p. 552, of all the clays, only attapulgite has been used extensively as an absorbent material; and at p.580, attapulgite clay, activated by moderate heating has been used as an absorbent for toxins. As far as applicant is aware, montmorillonite clays have not been used as a feed supplement to prevent the absorption of toxins into an animal's bloodstream. Montmorillonite clays are not known to provide any advantage in permitting almost unhindered weight gain in animals fed mycotoxin-contaminated grains, such as corn, as discovered by applicant.
An article describing the work leading to the present invention, carried out for this assignee by Dr. M. D. Lindemann et al., Associate Professor of Animal Science, Virginia Polytechnic Institute and State University, appears at J. Animal Science 68 (Suppl.1): 39, 1990, which article is not prior art to this application.
The montmorillonites are most effective with animal feeds contaminated with at least about 400 parts per billion (ppb) mycotoxin, and most significant amelioration of animal weight reduction is achieved at animal feed contamination levels of at least about 800 parts per billion mycotoxin, based on the total weight of contaminated feed. Some benefit is achieved, however, with montmorillonite clay fed to animals so long as the animal feed has sufficient mycotoxin contamination to cause measurably less weight gain in the animal, as compared to a controlled feed that is not contaminated, e.g. at least 50 to 100 parts per billion mycotoxin contamination. The montmorillonite should be fed to the animal in an amount sufficient to aid in the metabolic absorption of nutrients from the mycotoxin-contaminated animal feed, e.g. about 0.1% to about 1% based on the weight of the contaminated animal feed. Higher percentages of montmorillonite clay, based on the weight of mycotoxin-contaminated animal feed, can be used without any adverse effect, but without significant advantage.
Accordingly, one aspect of the present invention is to provide a method of increasing the amount of nutrients absorbed by an animal that is fed mycotoxin-contaminated food by feeding the animal a montmorillonite clay in addition to the contaminated food.
Another aspect of the present invention is to provide a method of increasing the weight gain achievable by feeding an animal mycotoxin-contaminated feed by simultaneously feeding the animal montmorillonite clay with the mycotoxin-contaminated feed.
Another aspect of the present invention is to provide a mycotoxin-contaminated animal food supplement comprising a montmorillonite clay for addition to the contaminated feed in an amount of at least about 0.1% based on the weight of the mycotoxin-contaminated animal feed.
The above and other aspects and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention.